How blockchain can improve public safety

By Paul Tatro

Apr 17, 2019

In 2014, tension over police-community relations in Boston, Chicago and New York made headlines. Riots and protests erupted after a series of high-profile police-involved shootings came to light, mostly captured through amateur cellphone videos. And while these videos stirred public sentiment, persistent issues with the admissibility, authenticity and interpretation of this digital evidence mitigated their effect on final verdicts in a court of law.

The case against George Zimmerman in Florida faltered after questions arose about when prosecutors became aware of digital evidence and why they had delayed sharing it with the defense. In the case of Michael Brown’s death in Ferguson, Mo., additional security footage was ruled inadmissible in court, but fueled riots when it was released in an independent documentary nearly three years after the case closed.

To avoid similar controversies in the future surrounding digital evidence, some authorities have started turning to a seemingly unlikely solution: blockchain technology.

Better handling of digital evidence is just one of the ways blockchain could help improve public safety. Indeed, blockchain holds the potential to help transform public safety by improving the way agencies handle their most sensitive evidence and data, enhancing interagency cooperation and promoting greater public trust in the integrity of investigations.

Understanding blockchain

To gauge how public safety agencies can harness blockchain, it helps to demystify this buzzworthy -- but often ill-understood -- technology. Blockchain is the underlying technology powering cryptocurrencies, but it is capable of much more.

At its core, a blockchain is a decentralized database shared across a network. Unlike centralized databases, however, records are only accepted after attaining group consensus. Following approval, records are stored in blocks and added to a public ledger with other blocks of recent records. The data in each block is passed through a hashing algorithm to generate an exclusive signature called a hash -- a digital fingerprint that uniquely identities the block. Each block’s hash value is not only dependent on all the data from the ordered records it contains, but also the hash value of the previous block. By capturing the hash value of the previous block, a connection is formed that links all blocks together in an unbroken chain. Once a block has been added to a blockchain, it can never be changed or deleted, which ensures the complete provenance of the data stored and makes blockchain ideal for historical record-keeping.

The bottom line: Blockchain provides a way to incorporate a variety of data from multiple sources, anonymize it, track it and ensure its authenticity without the need for third-party validation. The public-safety implications of such a technology are enormous.

Blockchain of custody

Given the proliferation of digital media, the question of what types of evidence are admissible in court, and how they should be handled, is increasingly complex. Cellphone video has played a pivotal role in scores of high-profile cases, as have recordings of 911 calls and footage captured from police body cameras. There’s no question this evidence is valuable, but ensuring its integrity and demonstrating an unbroken chain of custody -- the documentation that records the chronological sequence of the custody, control and disposition of a piece of evidence -- often proves difficult.

Establishing chain of custody for digital evidence is especially tricky. It can come from many sources and is particularly susceptible to tampering -- Photoshopping someone’s image into a crime scene, for example. Because it’s so easy to copy digital evidence, it can be difficult to identify originals and maintain evidence integrity throughout the chain of custody.

Blockchain is uniquely suited to tackling this challenge. In fact, the existing federal guidelines for handling digital evidence are surprisingly similar to the way blockchains work. When seizing a hard drive, for example, special personnel will scan the contents and use that data to generate a hash value.

Every string of data in a hash always generates the same hashed value, and no two strings of data will generate the same hash. Authorities can therefore copy the seized digital information to a new hard drive and use the existing hash to ensure the copy is exact. If one bit of information is altered on the copied drive, the hash generated from that data would not match the original hash, and investigators would know that someone had tampered with the data.

In the same way blockchains use hash values to verify linked blocks, digital forensics investigators use hashes to track digital evidence. Despite the similarities, blockchain presents multiple advantages over the current procedures. The principal advantage is the redundancy blockchain provides. Instead of relying on a team of specialists to first extract the data, then hash it, then track it, a “blockchain of custody” would allow for open submission of data to the blockchain, where it would be automatically verified by consensus, hashed and then entered into an immutable, shared public record.

Not only would a blockchain establish chain of custody by design, it would enable the processing of submissions from any agency on the network and enhance the ability to collaborate on that information openly and across jurisdictions. It also provides a heightened level of public trust in the integrity of the evidence, as any form of police tampering would prove impossible, thanks to the shared nature and immutability of the blockchain.

Removing collaborative roadblocks

In the United States, there are currently 11,955 separate law enforcement agencies. Data collection by various agencies has grown exponentially, but the ability to generate intelligence and then act upon this data continues to be hampered by bureaucratic inefficiencies, interagency divisions and siloed data. Establishing a unified data standard poses many challenges because it requires buy-in from so many agencies.

Blockchain circumvents this problem by enabling trustless collaboration and removing the need for centralized authority. The promise of an immutable, open public record of all data submitted could overcome a major hurdle for interagency collaboration.

Following the tragic Parkland, Fla., high school shooting, critics accused the FBI and local Sheriff’s Office of failing to coordinate. In the two years leading up to the shooting, the FBI received multiple tips about the suspicious behavior of future gunman Nelson Cruz. A ccording to the FBI, a tip phoned in just one month in advance of the shooting fell through the cracks after the public-access tip-line receiving the tip failed to follow protocol.

Blockchain's “smart contract” feature could ensure such protocols between agencies are always followed because they would be executed automatically by the system. Basically, a smart contract is a computer protocol that facilitates, verifies or enforces the performance of a contract or contract clause. In addition to formalizing information requests and opening investigations, smart contracts might also help balance data privacy and public safety.

Balancing privacy and safety

In the digital age, striking the right balance between privacy and safety poses a greater challenge than ever. In the year since the eruption of the Cambridge Analytica scandal, concerns surrounding data privacy have grown, as citizens grow increasingly troubled by the data collected about them and how it is being used -- whether by social media giants or law enforcement.

Take so-called “reverse search warrants,” which made headlines when a series of Dollar Tree stores in Virginia were robbed in 2018. Without a suspect, law enforcement officers approached a judge requesting the right to all GPS information from any phone within a certain radius of the crime scenes. This blanket search warrant captured thousands of records and possibly violated citizens’ Fourth Amendment rights.

Advocates defend the practice, claiming agencies first analyze anonymized data, then request another warrant to retrieve its identifying information. But lack of consistent regulation and public mistrust continues to cast doubt on these practices.

Blockchain would address this issue by enabling authorities to automatically anonymize the data they’ve gathered and implement rules within the system that would only allow authorized personnel to access sensitive information, such as evidence used to obtain a warrant.

Perhaps the most compelling case for blockchain is that it could enable other innovations by reducing friction between agencies and addressing privacy in a scalable way. The next step is to begin educating key decision-makers not only on the benefits of blockchain, but also about the current public safety issues this technology can effectively address.

Blockchain isn’t a panacea for all of law enforcement’s challenges -- but it can go a long way toward tackling some of the most pressing issues confronting the public safety community.